A read apparatus typically includes a read sensor and side magnetic bias structures that are between top and bottom shields. The read sensor is typically a tunneling magnetoresistive (TMR) sensor. The read sensor generally includes an antiferromagnetic (AFM) layer, a pinned layer, a tunneling barrier layer and a free layer. If the sensor is to be used in a current perpendicular to plane (CPP) configuration, then current is driven in a direction substantially perpendicular to the plane of the layers. In such cases, an insulating layer generally separates the sides of the read sensor from the side magnetic bias structures. The side magnetic bias structures are used to magnetically bias the free layer.
To fabricate the read apparatus, the read sensor stack is full film deposited. The read sensor stack includes the layers within the read sensor. In addition, a high temperature anneal may be performed in order to improve the crystal structure of one or more of the layers in the stack. A mask covering the region of the stack that will form the sensor is provided and the exposed portion of the stack removed. This is typically accomplished via ion milling. An insulating layer is grown or deposited and the magnetic bias structures provided. The mask may then be removed. Another mask that covers the read sensor and side magnetic bias structures is provided. This mask is used to define the stripe height of the read sensor and only extends the stripe height from the desired location of the air-bearing surface (ABS). The exposed portions of the read sensor stack and magnetic bias structures are removed. An insulating refill material, such as aluminum oxide, is deposited. Thus, the refill material adjoins, or shares interfaces with, the backs of the read sensor and side bias structures. Formation of the read apparatus may then be completed.
Although the read apparatus and method for fabricating the conventional read apparatus function, there are drawbacks. For example, the magnetic read apparatus is desired to be extended to higher areal densities. As a result, the dimensions of the structures are desired to be made smaller. Further, other recording technologies such as two-dimensional magnetic recording (TDMR) may be desired to be explored as part of higher areal density recording. In TDMR, multiple read sensors are used. Read sensors are typically offset in the down track and the cross-track directions so that adjacent tracks may be read. Because the read apparatus is built such that layers in the down track direction are formed later, fabrication of one sensor is typically completed before fabrication of the next sensor starts. Thus, the lower (earlier fabricated) sensor(s) of a TDMR read apparatus may undergo additional high temperature anneals during formation of subsequent sensor(s). These additional anneals may adversely affect performance and reliability of the lower sensor(s). Thus, performance, reliability and manufacturability of a TDMR read apparatus may be adversely affected.
Accordingly, what is needed is a system and method for improving the performance of a magnetic recording read apparatus.